Optimization of gold square-shaped nanopillars arrays for high-efficiency optronics

Parametric optimization of gold (Au) square-shaped nanopillars (AuNPLs) arrays deposited on glass substrate (AuNPLs/glass) was performed through optical characteristics for high-performance optical detection and biosensing purpose from visible to very near-infrared spectral (0.5 ≤λ≤0.8μm). This is aimed at predicting optimum parameters which result in strong enhancement for next-generation optronic devices. The optimization parameters were limited to the AuNPLs height (H), the interslit distance (W1), and the slit width (W2) in investigating the optical characteristics of reflectance, transmittance, and absorption. In achieving this, the extraordinary surface plasmon resonance (SPR) mechanism was explored using 3D finite-differential time-domain (3D-FDTD) algorithm. Based on the periodical nature of the AuNPLs array, periodic boundary conditions (PBCs) and stretched coordinate perfectly matched layers (SCPML) boundaries were employed for the computation region with a plane wave source injection at normal incidence (θ=0°). The results revealed new insights on the AuNPLs/glass structure and might inspire potential applications such as photodetectors and biosensors with optimum device achieved by controlling H from 0.1 to 1.0μm while W1=0.25μm and W2=0.1μm are kept constants and spectroscopy with optimum device by controlling W1 from 0.1 to 1.0μm while H=0.4μm and W2=0.1μm are maintained constants. Besides, application of biosensor performs sensitivity (S) of 380.14 nm/RIU (nanometer/refractive index unit) and 377.32 nm/RIU with corresponding highest figure of merit (FOM) of 8.02 RIU−1 and 11.11 RIU−1 for H=400 nm and H=600 nm, respectively.